The present invention relates to a method for optically measuring distance or speed, according to the preamble of claim 1, and to a device for optically measuring distance or speed or for a levelling device, according to the preamble of claim 4.
In devices for measuring distance and/or speed, the range—with otherwise identical technical properties—is the greater the higher the peak pulse power of the emitted laser pulses. On the other hand, for safety reasons, the peak pulse power cannot be increased without limit. The laser safety regulations permit higher peak pulse powers for wavelengths >1050 nm, i.e. in an invisible wavelength range, than for visible radiation.
Although this makes it possible to achieve longer ranges, a visible laser beam also has a number of advantages, such as                visualization of the measuring beam on the object;        possibility for checking and, if required, adjusting the position of the axis of the laser beam relative to the telescope axis;        reduction of the danger to the eye through the aversion reaction of an affected person, including the blink reflex.        